Exam Review Packet Student Version

Exam Review Packet – Student Version

Table of Contents

Directions

Periodic Table and Equations / Constants Sheet

Big Idea 1: The chemical elements are fundamental building materials of matter, and all matter can be understood in terms of arrangement of atoms. These atoms retain their identity in chemical reactions

Concepts - ATOMIC THEORY, BONDING AND PERIODIC TRENDS

Free Response Questions

Multiple Choice

Big Idea 2: Chemical and physical properties of materials can be explained by the structure and arrangement of atoms, ions, or molecules and the forces between them

Concepts - BONDING, LEWIS STRUCTURES AND INTERMOLECULAR FORCES

Free Response Questions

Multiple Choice Questions

Big Idea 3: Changes in matter involve the rearrangement and / or reorganization of atoms and / or the transfer of electrons

Concepts – ELECTROCHEMISTRY

Free Response Questions

Multiple Choice Questions

Big Idea 4: Rates of chemical reactions are determined by details of the molecular collisions

Concepts List – KINETICS

Free Response Questions

Multiple Choice Questions

Big Idea 5: The laws of thermodynamics describe the essential role of energy and explain and predict the direction of changes in matter

Concepts – THERMODYNAMICS

Free Response Questions

Multiple Choice Questions

Big Idea 6: Any bond or intermolecular attraction that can be formed can be broken. These two processes are in a dynamic competition, sensitive to initial conditions and external perturbations.

Concept List – EQUILIBRIUM

Free Response Questions

Multiple Choice Questions

Laboratory

Concepts – LABORATORY QUESTIONS – contained in several Big Ideas and the Science Practices

Free Response Questions

Multiple Choice

Directions

Multiple Choice Section

In section 1, there are 60 multiple choice questions. These questions represent the knowledge and skills students should know, understand, and be able to apply. Students will be given a periodic table and an equations and constants list to use during this section.

For all questions, assume that the temperature is 298 K, the pressure is 1.00 atmosphere, and solutions are aqueous unless otherwise specified.

Free Response section

Section II Directions: Questions 1 through 3 are long constructed response questions that should require about 20 minutes to answer. Questions 4 through 7 are short constructed response questions that should require about 7 minutes each to answer. Read each question carefully and write your response in the space provided following each question. Your responses to these questions will be scored on the basis of the accuracy and relevance of the information cited. Explanations should be clear and well organized. Specific answers are preferable to broad, diffuse responses. For calculations, clearly show the method used and the steps involved in arriving at your answers. It is to your advantage to do this, since you may obtain partial credit if you do and you will receive little or no credit if you do not.

Periodic Table and Equations / Constants Sheet

Big Idea 1: The chemical elements are fundamental building materials of matter, and all matter can be understood in terms of arrangement of atoms. These atoms retain their identity in chemical reactions

Concepts - ATOMIC THEORY, BONDING AND PERIODIC TRENDS

1.Quantum Numbers, electron configurations, Hund’s rule, orbital diagrams

2 Trends of the periodic table a) size for atoms and ions b) size of ions c) IE, EA, EN

3.Effective nuclear charge (Zeff ) increases as more protons added to same

energy level Zeff is a comparison tool. Coulomb’s Law F=kqq/d2

4.Effective nuclear charge (Zeff ) decreases as more shielding electrons are

present.

5.When students talk about EN differences they are talking about bonds

(within a molecule), we need them to talk about IMF (between molecules )

6.Students often talk about atoms “wanting to gain/lose electrons”, being happy,

Full, rather than having a stable octet, complete energy level.

7. Correct use of spectroscopy (UV,IR,VIS,PES )

8.Vocabulary

IE (ionization energy)

EN (electronegativity)

EA (electron affinity)

Free Response Questions

1987 Q5

5.Use the details of modern atomic theory to explain each of the following experimental observations.

a.Within a family such as the alkali metals, the ionic radius increases as the atomic number increases.

b.The radius of the chlorine atom is smaller than the radius of the chloride ion, Cl¯. (Radii: Cl atom = 0.99 Å; Cl= ion = 1.81 Å)

c.The first ionization energy of aluminum is lower than the first ionization energy of magnesium. (First ionization energies: 12Mg = 7.6 ev, 13Al = 6.0 ev)

d.For magnesium, the difference between the second and third ionization energies is much larger than the difference between the first and second ionization energies. (Ionization energies, in electron-volts, for Mg: 1st = 7.6, 2nd = 14, 3rd = 80)

1987 Q9

9.Two important concepts that relate to the behavior of electrons in atomic system are the Heisenberg uncertainty principle and the wave-particle duality of matter.

a.State the Heisenberg uncertainty principle as it relates to determining the position and momentum of an object.

b.What aspect of the Bohr theory of the atom is considered unsatisfactory as a result of the Heisenberg uncertainty principle?

c.Explain why the uncertainty principle or the wave nature of particles is not significant when describing the behavior of macroscopic objects, but is very significant when describing the behavior of electrons.

1994 Q9

9.Use principles of atomic structure and/or chemical bonding to answer of each of the following.

a.The radius of the Ca atom is 0.197 nanometers; the radius of the Ca2+ ion is 0.099 nanometer. Account for this difference.

b.The lattice energy of CaO(s) is -3,460 kilojoules per mole; the lattice energy for K2O(s) is -2,240 kilojoules per mole. Account for this difference.

c.Explain the difference between Ca and K in regard to:

i.their first ionization energies.
ii.their second ionization energies.

Multiple Choice

18.Which of the following elements has the largest first ionization energy?

a. Li

b.Be

c.B

d.C

e.N

22.How many protons, neutrons, and electrons are in an 5626Fe atom?

Protons Neutrons Electrons

a. 26 30 26

b.265626

c.302630

d.562626

e.568256

23. Which of the following is the electron configuration of an excited atom that is likely to emit a quantum of energy?

a.1s2 2s22p6 3s23p1

b.1s2 2s22p6 3s23p5

c.1s2 2s22p6 3s2

d.1s2 2s22p6 3s1

e.1s2 2s22p6 3s13p1

57. Which of the following lists Mg, P, and Cl in order of increasing atomic radius?

a.Cl < P < Mg

b.Cl < Mg < P

c.Mg < P < Cl

d.Mg < Cl < P

e.P < Cl < Mg

Big Idea 2: Chemical and physical properties of materials can be explained by the structure and arrangement of atoms, ions, or molecules and the forces between them

Concepts -BONDING,LEWIS STRUCTURES AND INTERMOLECULAR FORCES

1. Ionic bonds

2.Covalent bonds, Lewis structures, geometric shapes, bond polarity, molecular polarity, resonance, hybridization, London dispersion forces (LDF), inter vs. intramolecular forces

3.Intermolecular Forces (IMF) are between molecules and help explain differences in FP, BP, solids, liquids, gases, and solubilities.

1. ion – ion
2. dipole – dipole with H bonding
3. dipole – dipole
4. London dispersion forces ( LDF )

4.When students talk about EN differences they are talking about bonds(within a molecule), we need them to talk about IMF (between molecules )

5.Molecular polarity depends on bond polarity and shape of the molecule

6.Vocabulary

IE (ionization energy)

EN (electronegativity)

EA (electron affinity)

Free Response Questions

2013 Q5

5.Methanamide, CH3NO, is a liquid at 25 oC.

a.The complete Lewis electron dot diagram for methanamide is shown below.

i.In the molecule, angle x is not 180o. Estimate the observed angle. Justify your answer.

ii.In the molecule, angle y is not 90o. Explain why in terms of electron domains (VSEPR model).

b.Consider a molecule with the formula CH2O2. The structure of this molecule has a geometry around the carbon atom similar to the geometry around carbon in methanamide. In the box provided below, draw the complete Lewis electron dot diagram for the molecule.

2013 PR Q6

6.

The structures of a water molecule and a crystal of LiCl(s) are represented above. A student prepares a 1.0 M solution by dissolving 4.2 g of LiCl(s) in enough water to make 100 mL of solution.

a.In the space provided below, show the interactions of the components of LiCl(aq) by making a drawing that represents the different particles present in the solution. Base the particles in your drawing on the particles shown in the representations above. Include only one formula unit of LiCl and no more than 10 molecules of water. Your drawing must include the following details.

Identity of ions (symbol and charge)

The arrangement and proper orientation of the particles in the solution

2013 PR Q7

7.HIn(aq) + H2O(l)  In-(aq) + H3O+(aq)

Yellowblue

The indicator HIn is a weak acid with a pKa value of 5.0. It reacts with water as represented in the equation above. Consider the two beakers below. Each beaker has a layer of colorless oil (a nonpolar solvent) on top of a layer of aqueous buffer solution. In beaker X the pH of the buffer solution is 3, and in beaker Y the pH of the buffer solution is 7. A small amount of HIn is placed in both beakers. The mixtures are stirred well, and the oil and water layers are allowed to separate.

a.What is the predominant form of HIn in the aqueous buffer in beaker Y, the acid form or the conjugate base form? Explain your reasoning.

b.In beaker X the oil layer is yellow, whereas in beaker Y the oil layer is colorless. Explain these observations in terms of both acid-base equilibria and interparticle forces.

2010 Q5

5.Use the information in the table below to respond to the statements and questions that follow. Your answersshould be in terms of principles of molecular structure and intermolecular forces.

a.Draw the complete Lewis electron dot diagram for ethyne in the appropriate cell in the table above.

b.Which of the four molecules contains the shortest carbon-carbon bond? Explain.

c.A Lewis electron dot diagram of a molecule of ethanoic acid is given below. The carbon atoms in the molecule are labeled x and y, respectively.

Identify the geometry of the arrangement of atoms bonded to each of the following.

i.Carbon x

ii.Carbon y

d.Energy is required to boil ethanol. Consider the statement “As ethanol boils, energy goes into breaking C-C bonds, C-H bonds, C-O bonds, and O-H bonds.” Is the statement true or false? Justify your answer.

e.Identify a compound from the table above that is nonpolar. Justify your answer.

f.Ethanol is completely soluble in water, whereas ethanethiol has limited solubility in water. Account for the difference in solubilities between the two compounds in terms of intermolecular forces.

2011B #6

6.Use principles of molecular structure, intermolecular forces, and kinetic molecular theory to answer the following questions.

a.A complete Lewis electron dot diagram of a molecule of ethyl methanoate is given below.

i.Identify the hybridization of the valence electrons of the carbon atoms labeled Cw.

ii.Estimate the numerical value of the Hy – Cx – O bond angle in an ethyl methanoate molecule. Explain the basis of your estimate.

b.Ethyl methanoate, CH3CH2OCHO, is synthesized in the laboratory from ethanol, C2H5OH, and methanoic acid, HCOOH, as represented by the following equation.

C2H5OH(l) + HCOOH(l)  CH3CH2OCHO(l) + H2O(l)

i. In the box below, draw the complete Lewis electron dot diagram of a methanoic acid molecule.

ii.In the box below, draw the complete Lewis electron dot diagrams of a methanoic acid molecule and a water molecule in an orientation that allows a hydrogen bond to form between them.

Hydrogen Bonding between Methanoic Acid and Water

2011 A Q5

5.Hydrazine is an inorganic compound with the formula N2H4.

a.In the box below, complete the Lewis electron-dot diagram for the N2H4 molecule by drawing in all the electron pairs.

b.On the basis of the diagram you complete in part (a), do all six atoms in the N2H4 molecule lie in the same plane? Explain.

c.The normal boiling point of N2H4 is 114 oC, whereas the normal boiling point of C2H6 is

-89 oC. Explain, in terms of the intermolecular forces present in each liquid, which the boiling point of N2H4 is so much higher than that of C2H6.

d.Write a balanced chemical equation for the reaction between N2H4 and H2O that explains why a solution of hydrazine in water has a pH greater than 7.

N2H4 reacts in air according to the equation below.

N2H4(l) + O2(g)  N2(g) + 2 H2O(g)ΔHo = -534 kJ mol-1

e.Is the reaction an oxidation-reduction, acid-base, or decomposition reaction? Justify your answer.

f.Predict the sign of the entropy change, ΔS, for the reaction. Justify your prediction.

g.Indicate whether the statement written below is true or false. Justify your answer.

The large negative ΔHo for the combustion of hydrazine results from the large release of energy that occurs when the strong bonds of the reactants are broken.

2012 Q5 (2nd half)

An experiment is performed to compare the solubilities of I2(s) in different solvents, water and hexane (C6H14). A student adds 2 mL of H2O and 2 mL of C6H14 to a test tube. Because H2O and C6H14 are immiscible, two layers are observed in the test tube. The student drops a small, purple crystal of I2(s) into the test tube, which is then corked and inverted several times. The C6H14 layer becomes light purple, while the H2O layer remains virtually colorless.

d.Explain why the hexane layer is light purple while the water layer is virtually colorless. Your explanation should reference the relative strengths of interactions between molecules of I2 and the solvents H2O and C6H14, and the reasons for the differences.

e.The student then adds a small crystal of KI(s) to the test tube. The test tube is corked and inverted several times. The I- ion reacts with I2 to form the I3- ion, a linear species.

i.In the box below, draw the complete Lewis electron-dot diagram for the I3- ion.

ii.In which layer, water or hexane, would the concentration of I3- be higher? Explain.

Multiple Choice Questions

Questions 4-7 refer to the following species.

a.H2O

b.NH3

c.BH3

d.CH4

e.SiH4

4. Has two lone pairs of electrons

5. Has a central atom with less than an octet of electrons

6.Is predicted to have the largest bond angle

7. Has a trigonal-pyramidal molecular geometry

42. Which of the following lists the substances F2, HCl, and HF in order of increasing boiling point?

a. HF < HCl < F2

b.HF < F2 < HCl

c.HCl < F2 < HF

d.HCl < HF < F2

e.F2 < HCl < HF

47. Which of the following is an isomer of CH3OCH3?

a.CH3CH3

b.CH3COOH

c.CH3CH2OH

d.CH3CH2CH3

e.CH3CH2OCH2CH3

49. Which of the following substances has the greatest solubility in C5H12(l) at 1 atm?

a.SiO2(s)

b.NaCl(s)

c.H2O(l)

d.CCl4(l)

e.NH3(g)

54. High solubility of an ionic solid in water is favored by which of the following conditions?

I. The existence of strong ionic attractions in the crystal lattice

II. The formation of strong ion-dipole attractions

III. An increase in entropy upon dissolving

a.I only

b.I and II only

c.I and III only

d.II and III only

e.I, II, and III

71. Which of the following molecules contains exactly three sigma (σ) bonds and two pi (π)bonds?

a.C2H2

b.CO2

c.HCN

d.SO3

e.N2

73. Resonance is most commonly used to describe the bonding in molecules of which of the following?

a.CO2

b.O3

c.H2O

d.CH4

e.SF6

Big Idea 3: Changes in matter involve the rearrangement and / or reorganization of atoms and / or the transfer of electrons

Concepts–ELECTROCHEMISTRY

1.oxidation / reduction – balancing equations (review)

2.galvanic cells – {positive, Red Cat}

3.electrolytic cells

4.current, charge, Faradays, (voltage / EMF) (amps, coulombs and volts – unit problem)

5.cell notation

6.salt bridge – “balance of charge” not electron balance,

Good salt bridge materials are soluble salts, not easily oxidized or reduced, doesn’t interfere with given redox reaction, ie complex ion formation or precipitation

7.Eo and thermodynamically favored

8.ΔGo = - n F Eo

9.E = Eo – (0.059 / n) log Kc

10.Vocabulary –

Anode

Cathode

Galvanic

Voltaic

CONCENTRATION UNITS OF SOLUTIONS / COLLIGATIVE PROPERTIES(conceptual only)

1.Molarity M = mole of solute/ L of solution

2. mole fraction = xa = mole of a /total moles in solution

3.∆ FP ↓ = (kf ) ( m ) ( i ) freezing point depression

4.∆ BP ↑ = ( kb ) (m ) ( i ) boiling point elevation

5.∏ = ( M ) (R ) ( T ) ( i ) osmotic pressure

6.Vapor Pressure Lowering = VPL = (xsolvent) VP pure solvent

i = Van’t Hoff factor

for organic solutes nonelectrolytes i = 1

for electrolytes i = 2,3,4… NaCl i = 2 H2SO4 i = 3

AlCl3 i = 4

Free Response Questions

2013 PR Q1

1.

A student performs an experiment in which the conductivity of a solution of Ba(OH)2 is monitored as the solution is titrated with 0.10 M H2SO4. The original volume of the Ba(OH)2 solution is 25.0 mL. A precipitate of BaSO4 (Ksp = 1.0 x 10-10) formed during the titration. The data collected from the experiment are plotted in the graph above.

a.As the first 30.0 mL of 0.10 M H2SO4 are added to the Ba(OH)2 solution, two types of chemical reactions occur simultaneously. On the lines proved below, write the balanced net ionic equations for (i) the neutralization reaction, and (ii) the precipitation reaction.

i.Equation for neutralization reaction______

ii.Equation for precipitation reaction______

b.The conductivity of the Ba(OH)2 solution decreases as the volume of added 0.10 M H2SO4 changes form 0.0 mL to 30.0 mL.

i)Identify the chemical species that enable the solution to conduct electricity as the first 30.0 mL of 0.10 M H2SO4 are added.

ii)On the basis of the equations you wrote in part a, explain why the conductivity decreases.

c.Using the information in the graph, calculate the molarity of the original Ba(OH)2 solution.

d.Calculate the concentration of Ba2+(aq) in the solution at the equivalence point (after exactly 30.0 mL of 0.10 M H2SO4 are added).

e.The concentration of Ba2+(aq) in the solution decreases as the volume of added 0.10 M H2SO4 increases from 30.0 mL to 31.0 mL. Explain.

2013 PR Q 6

b.The student passes a direct current through the solution and observes that chlorine gas is produced at the anode. Identify the chemical species produced at the cathode and justify your answer using the information given in the table below.

Half reactionStandard reduction potential at 25 oC (V)

Li+(aq) + e- Li(s)-3.05

2 H2O(l) + 2 e- H2(g) + 2 OH-(aq)-0.83

2010 B Q2.

5 Fe2+(aq) + MnO4- (aq) + 8 H+(aq)  5 Fe3+(aq) + Mn2+(aq) + 4 H2O(l)

A galvanic cell and the balanced equation for the spontaneous cell reaction are shown above. The two reduction half reactions for the overall reaction that occurs in the cell are shown in the table below.

Half reactionEo (V) at 298 K

Fe3+(aq) + e- Fe2+(aq)+ 0.77 V

MnO4-(aq) + 8 H+(aq) + 5 e- Mn2+(aq) + 4 H2O(l)+ 1.49

a.On the diagram, clearly label the cathode.

b.Calculate the value of the standard potential, Eo, for the spontaneous cell reaction.

c.How many moles of electrons are transferred when 1.0 mol of MnO4-(aq) is consumed in the overall cell reaction?

d.Calculate the value of the equilibrium constant, Keq, for the cell reaction at 25 oC. Explain what the magnitude of Keq tells you about the extent of the reaction.

Three solutions, one containing Fe2+(aq),one containing MnO4-(aq) and one containing H+(aq), are mixed in a beaker and allowed to react. The initial concentrations of the species in the mixture are 0.60 M Fe2+(aq), 0.10 M MnO4-(aq), and 1.0 M H+(aq).

e.When the reaction mixture has come to equilibrium, which species has the higher concentration, Mn2+(aq) or MnO4-(aq)? Explain.